Substrate processing apparatuses (thermal processing apparatuses) used for manufacturing semiconductors, flat panel displays, photovoltaic cells, and the like may be apparatuses that perform an essential thermal processing process for crystallizing and phase-changing a predetermined thin film that is deposited on a substrate such as a silicon wafer or a glass substrate. Typically, in case of manufacturing liquid crystal displays or thin-film crystalline silicon photovoltaic cells, there is a silicon crystallization apparatus for crystallizing amorphous silicon deposited on the a substrate into poly silicon.
To perform the above-described crystallization process (thermal processing process), a thermal processing apparatus that is capable of heating a substrate on which a predetermined thin film is formed is needed. For example, a temperature of minimum about 550° C. to about 600° C. is required for crystallizing amorphous silicon. Here, the thermal processing may means a process for heating an object or substrate at a desired temperature, i.e., a temperature of about 350° C. to about 1,300° C. The thermal processing on the semiconductor substrate may include, for example, heat processing, annealing, diffusing or driving of a dopant material, chemical deposition, i.e., deposition or growth of a material layer such as CVD, and an etching or removing of a material.
Typically, a substrate processing apparatus may be classified into a single wafer type substrate processing apparatus in which thermal processing is performed on one substrate and a batch type substrate processing apparatus in which thermal processing is performed on a plurality of substrates. The single wafer type substrate processing apparatus has an advantage in that its structure is simple. However, the single wafer type substrate process apparatus may be deteriorated in productivity. Thus, the batch type substrate processing apparatus may be in the spotlight.
The batch type substrate processing apparatus include a substrate loading boat for loading a plurality of substrates into a chamber to improve process processing performance. In the batch type substrate processing apparatus, since an edge of the substrate is locally mounted in a slot during the process, a film for the semiconductor process may be formed on a boat or slot that supports both surfaces and a lower portion of the semiconductor substrate during the film formation process.
Thus, when the substrate is unloaded after the film formation process for manufacturing a semiconductor is completed, the film integrally connected to the substrate and the slot may be broken. Thus, when the film is broken, particles may occur, and mechanical stress on the rear surface of the substrate may more increase to cause bending of the substrate. In addition, since film uniformity on the rear surface of the semiconductor substrate is significantly less than that on a front surface, this may cause a lot of trouble in following processes, particularly, a photolithography process.